1. Field of the Invention
This invention relates to an inkjet ink composition.
2. Description of the Related Art
In recent years, a recording apparatus employing an inkjet system has been widely utilized at home, in the office and industry. In the recording apparatus employing an inkjet system, an ink to be employed therein is selected from a water-based ink, a non-aqueous ink and a UV ink depending on applications. Since the water-based ink is cheap and excellent in safety, it is widely used for various applications. The water-based ink however cannot be dried quickly enough to be applied to a high-speed printing. Moreover, when the water-based ink is employed for printing on a plain paper (PPC paper), a phenomenon of so-called cockling where the paper is cockled after the ink has been dried occurs. Since the UV ink can be quickly cured as it is irradiated with ultraviolet ray, the UV ink is suited for use in the printing on a non-absorptive media or in a high-speed printing. However, it is required, in the application of the UV ink, to employ an ultra-violet ray irradiating apparatus which is large in scale and in power consumption.
Whereas, when an oil based ink is employed for the printing on a plain paper, the ink penetrates into a recording paper within a short period of time as soon as drops of ink discharged from an inkjet head are impinged against the paper. Therefore, the oil based ink is suited for use in a high-speed printing without necessitating any special mechanism and is capable of obtaining excellent printed images without generating cockling.
However, since the solvent included in an oil based ink is hardly volatilized, when the oil based ink is printed on a plain paper, the solvent leaves inside the paper, thus raising a problem that printed portions are permitted to look through from the reverse side of paper (or a phenomenon of so-called strike-through). This problem however is now being overcome by optimizing the physical properties of the solvent.